TWO STROKE SMALL ENGINE TEST RIG DESIGN AND ITS ENGINE PERFORMANCE ANALYSIS ROSMAN RAZALI

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1 i TWO STROKE SMALL ENGINE TEST RIG DESIGN AND ITS ENGINE PERFORMANCE ANALYSIS ROSMAN RAZALI A report submitted in partial fulfillment of the requirements for the award of the degree of Bachelor Of Mechanical Engineering Faculty of Mechanical Engineering University Malaysia Pahang NOVEMBER 2009

2 ii SUPERVISOR S DECLARATION We hereby declare that we have checked this project and in our opinion this project is satisfactory in terms of scope and quality for the award of the degree of Bachelor of Mechanical Engineering with Automotive. Signature: Name of Supervisor: Position: Lecturer Date: 24 November 2009

3 iii STUDENT S DECLARATION I hereby declare that the work in this thesis is my own except for quotations and summaries which have been duly acknowledged. The thesis has not been accepted for any degree and is not concurrently submitted for award of other degree. Signature: Name: Rosman Bin Razali ID Number: MH06025 Date: 24 November 2009

4 iv Dedicated to my beloved Father, Mother, and Friends

5 v Acknowledgements In the name of Allah, the Most Benevolent and the most Merciful. Every sincere appreciation and gratitude is only to God. Only by His Kindness and Guidance that this thesis is finally completed.in preparing this thesis, I was in contact with many people and academicians. They have contributed toward my understanding, thought, and also guidance. In particular, I wish to express my sincere appreciation to my main thesis supervisor, P. Madya Dr. Rosli Bin Abu Bakar and my co-supervisor Mr. Aguk Zuhdi Muhammad Fathallah for their valuable guidance, advice and continuous encouragement, constructive criticism and suggestion throughout this project. Without their continued support and interest, this thesis would not have been the same as presented here. My sincere also extends to all my beloved family especially my parents, Razali Bin Hussin and Rokiah Binti Bakar because if not of their prayer and support I would not be here and done this thesis. Moreover, I would like to thanks for all my colleagues and other who has provides assistance at various occasions. Their view tips are useful indeed in helping me to achieve doing this thesis. My dedicated also fly to all Mechanical s Engineer Assistant for provide guidance for me to accomplice this task especially to Mr. Ujang and Mr. Nizam. Not forgot also to Pakcik Mat, KK2 s hostel cleaner who is very supporting person. Because of his courageous, I can still stand to complete this thesis. With his experience, I gain too many knowledge in conducting this experiment. Hence, to all people that direct or indirectly involve accomplishing my thesis I been sincerely thankful.

6 vi Abstract This thesis is about how to perform an analysis of 30.5cc two stroke engine without using dynamometer. As we know, dynamometer is very expensive in the market and some way need to be build to perform engine performance analysis based on functionality of dynamometer. Hence, dynamometer been replaced with alternator where it is very cheap and easy to find in market. So, engine test rig had been designed before can proceed to fabrication process. Some sketches software had used like autocad and solidwork to draft out the shape of engine test rig. Materials selection also included in this designed process. Variable loads will be given at constant engine speed to see whether performance of engine will decrease or increase. Here, we can analyze at which engine speed is the optimum of performance from this small engine. So, some losses like power and fuel can be decrease.

7 vii Abstrak Tesis ini adalah mengenai bagaimana cara untuk menganalisis prestasi enjin dua lejang 30.5cc tanpa mengunakan dynamometer. Sebagaimana yang kita ketahui, harga dynamometer di pasaran adalah sangat tinggi. Tambahan pula, saiz enjin yang kecil adalah tidak dapat ditampung oleh saiz dynamometer yang besar. Oleh yang demikian, satu alternatif lain dikaji. Alternator telah diguna bagi menggantikan dynamometer. Tambahan pula, ia senang diperoleh dan harganya murah di pasaran. Dengan menggunakan Auto-Cad dan solidwork, draf atau gambaran asal mengenai reka bentuk rakit enjin dapat diihat dengan jelas. Pemilihan dalam memperoleh setiap barang seperti alternator juga termasuk di dalam mereka bentuk rakit enjin sebelum dapat meneruskan uji kaji. Pada kelajuan enjin yang tetap, variasi beban akan diberikan kepada enjin untuk mengukur sejauh mana keupayaan enjin tersebut berfungsi. Di sini juga, kita dapat lihat kuasa dari enjin akan berkurang atau meningkat setelah diberikan sejumlah beban. Oleh yang demikian, kehilangan keupayaan enjin seperti kuasa dan minyak dapat dikurangkan.

8 viii TABLE OF CONTENTS SUPERVISOR S DECLARATION STUDENT S DECLARATION ACKNOWLEDGEMENTS ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS Page ii iii v vi vii viii xi xii xiii CHAPTER 1 INTRODUCTION 1.1 Background Problem Statement Objective Scope 2 CHAPTER 2 LITERATURE REVIEW 2.1 Introduction Basic Concept of Engine Performance Foundation of Engine Performance Testing The Importance of Engine Performance Testing Development of Engine Performance Testing Dynamometer Principle of Operation Types of Dynamometer 12

9 ix Eddy Current Type Absorber Magnetic Power Brake Hysteresis Brake Water Brake Electric Motor or Generator Performing Engine Testing Using Dynamometer General Testing Methods 16 CHAPTER 3 METHODOLOGY 3.1 Introduction Development of Dynamometer Flow Chart Materials Selection Engine Specifications Alternator Selection Other Materials Designing Small Engine Test Rig Fabrication of Small Engine Test Rig Formula Calibration Engine Speed Calibration Engine Power Calibration Data Collecting 31 CHAPTER 4 RESULTS AND DISCUSSION 4.1 Introduction Results Sample Calculation Data Analysis and Discussion 38

10 x CHAPTER 5 CONCLUSION AND RECOMMENDATIONS 5.1 Introduction Conclusion Recommendation 48 REFERENCES 49 APPENDIX 51

11 xi LIST OF TABLES Table No. Title Page Table 3.1 Engine specification 21 Table 3.2 Several model of alternator 22 Table 3.3 Calibration of angular velocity 30 Table 3.4 Calibration of voltmeter 31 Table 3.5 Calibration of voltmeter 31 Table 4.1 Result of engine speed for 1000 rpm 33 Table 4.2 Result of engine speed for 2000 rpm 34 Table 4.3 Result of engine speed for 3000 rpm 34 Table 4.4 Result of engine speed for 4000 rpm 35 Table 4.5 Result of engine speed for 5000 rpm 35 Table 4.6 Result of engine speed for 6000 rpm 35 Table 4.7 Result of engine speed for 7000 rpm 36

12 xii LIST OF FIGURES Figure No. Title Page Fig 2.1 Example of medium engine test rig 5 Fig 2.2 Titan Test Stand 7 Fig 2.3 Fig 2.4 Fig 2.5 Typical shape of power, torque characteristics of a conventional size 2/4 - stroke engine Electrical dynamometer setup showing engine, torque measurement arrangement and tachometer Schematic shows of a water brake which is actually a fluid coupling with the housing restrained from rotating and similar to a water pump with no outlet Fig 2.6 Example of Electric Motor Dynamometer 15 Fig 2.7 Example plotted graph 17 Fig 3.1 Flow chart 20 Fig 3.2 Initial draft of small engine test rig 23 Fig 3.3 Draft of engine test rig 24 Fig 3.4 Small two stroke engine used 25 Fig 3.5 Modification on shaft by putting the pulley 25 Fig 3.6 Alternator holder 26 Fig 3.7 Installing the alternator 26 Fig 3.8 Front view of test rig without timing belt 26 Fig 3.9 Front view of test rig with timing belt 27 Fig 3.10 Upper view of engine test rig 27 Fig 3.11 Electric circuit as load 28

13 xiii Fig 3.12 Engine test rig setup 28 Fig 3.13 Tachometer s laser detection 32 Fig 3.14 Conducting the tachometer 33 Fig 4.1 Graph of SFC against Load for speed 1000 rpm 38 Fig 4.2 Graph of SFC against Load for speed 2000 rpm 39 Fig 4.3 Graph of SFC against Load for speed 3000 rpm 39 Fig 4.4 Graph of SFC against Load for speed 4000 rpm 40 Fig 4.5 Graph of SFC against Load for speed 5000 rpm 41 Fig 4.6 Graph of SFC against Load for speed 6000 rpm 41 Fig 4.7 Graph of SFC against Load for speed 7000 rpm 42 Fig 4.8 Comparison of SFC with variable speed 43 Fig 4.9 Graph of Power against Speed at full load 43 Fig 4.10 Graph of Torque against Speed at full load 44 Fig 4.11 Graph of SFC against Speed at full load 45

14 xiv LIST OF ABBREVITIONS AC BHP bmep DC EC ICE imep PAU RPM SFC SI SVM VCR Alternating current Brake horse power Mean effective pressure, brake Direct current Eddy current Internal combustion engine Mean effective pressure, indicated Power absorber unit Rotational per minute Specific fuel consumption Spark ignition Support vehicle machine Vehicle compression ratio

15 1 CHAPTER 1 INTRODUCTION 1.1 BACKGROUND The performance of engine study is very important to improve engines product, research, and to make service for customer. Every product of engine has it own performance. However, this engine needs to test using engine test bed. Now days engine test bed or some time call as engine test rig are spiritedly from medium to large. These test bed are best to used for test medium to large engine. Seemly not sufficient for very small engine, not only more money need to invest but also less precisian resulted. For that reason, it needs to design small engine test rig to study the performance of small engine. Most of engine test beds are available to test from medium to large engine. It is very difficult to test performance of a small or a very small engine. Although it is possible to test a small engine using larger engine test rig but it will be insufficient result. Because imprecision performance result of small engine could be inflict for the customer. Usually to study performance of small engine are using simulation. Although the result can predicted performance of engines but for perfect result is using experiment methods. To test a small engine should use a small engine test rig. It could have more accurate result. However, lately it is very difficult to look small engine test rig in the market. Because the demand are very small they do not product small engine test rig. If we would like to test performance of small engine we should design by own engine

16 2 test rig. This research will be study a performance vary small engine using experiment technique with small engine test rig. To conduct the performance engine should be start from to design small engine test rig, fabricated the design, and finally an analysis performance of the engine. The capacity of cylinder of an engine is about 30 CC. For that reason it is need specific small engine rig design. 1.2 PROBLEM STATEMENT How to studies the performance a small two stroke engine with experiment technique. The budget of the research is limited but the result should be accurate. 1.3 OBJECTIVE a. To design small engine test rig for two stroke 30 CC engine test rig using alternator as dynamometer. b. To build the small engine test rig c. To test a performance of the engine 1.4 SCOPE 1. Literature reviews 2. Survey to mechanical engineering laboratories and also to shop market. 3. To design small engine test rig using solid work software. 4. To collect and select cheapest components and materials of engine test rig. 5. To build a small engine test rig. 6. To do experiment for conducting data 7. To study the performance of the engine. 8. To analysis of the performance 9. To write of the report

17 3 CHAPTER 2 LITERATURE REVIEW 2.1 INTRODUCTION This chapter will briefly explain about basic concept of engine performance, foundation of engine performance testing, the importance of engine performance testing, development of engine performance testing, principle of dynamometer and a few related studies and journals that have been done by current researchers. All this information is important before furthering to the analysis and study later. 2.2 BASIC CONCEPT OF ENGINE PERFORMANCE Engine performance characteristics are convenient graphical presentation of an engine performance. They are constructed from the data obtained during actual test runs of the engine and are particularly useful in comparing the performance of one engine with that of another. In this section some of the important performance characteristics of the SI engine are discussed. It is to be noted that there is a certain speed, within the speed range of particular engine, at which charged inducted per cylinder per cycle will be the maximum. At this point, the maximum force can therefore be exerted on the piston. For all practical purpose, the torque or engine capacity to do work also will maximum at this point.

18 4 As the speed of the engine is increased above this speed the quantity of the indicated charge will decrease. However, the power output of the engine increases with the speed due to more number of cycles is executed per unit time. It should be note that the air consumption will continue to increase with increased engine speed until some point is reached where the charge per cylinder per stroke decreases very rapidly than the number of the strokes per unit time is increasing. Engines are so designed that the maximum air consumption point is not reached within the operating speed of the engine. Increase in air consumption means that the increased quantities of fuel can be added per unit time increasing the power output. 2.3 FOUNDATION OF ENGINE PERFORMANCE TESTING Engine performance is really a relative term. Normally it is represented by typical characteristic curves which are functions of engine operating parameters. The term performance usually means how well an engine is doing its job in relation to the input energy or how effectively it is provides useful energy in relation to some other comparable engines. Most of the testing of engines for their performance characteristics takes place under laboratory condition. The engine is connected to a power-absorbing device, called a dynamometer (G. P. Blair, 1996). However, the performance characteristics of power, torque, fuel consumption rate, and air consumption rate, at various engine speeds, are recorded (J.B. Heywood, 1988). There are so many types of dynamometers; the principle of any dynamometer operation is to allow the casing to swing freely (A.J. Martyr and M.A. Plint, 2007). The reaction torque on the casing, which is exactly equal to the engine torque, is measured on a level length, L, from the centerline of the dynamometer as force, F. This restrains the outside casing from revolving, or the torque and power would not be absorbed (G. P. Blair, 1996 and A.J. Martyr and M.A. Plint, 2007).

19 5 Fig 2.1: Example of medium engine test rig According to reference, engine performance theory could be divided to two areas such as to learn performance engine using dynamometer (G. P. Blair, 1996, J.B. Heywood, 1988 and A.J. Martyr and M.A. Plint, 2007), and to repair and maintain engine trough diagnostic analysis system with the result is the efficient operation of engines of all designs (J. Erjavec, 2006). Both theories have different objectives. First, to learn performance engine used dynamometer. The goal is could be developed engine performance or may be also give service to customers for selected an engine. Second, is to monitoring of engine in order to have the efficient operation using diagnostic techniques. Then, there are several factors that must considered in evaluating the performance of the engine. Most of them are maximum power or torque available at each speed within the useful range of speed. Some range of the power output at constant speed for stable operation of the engine must be decided. The different speeds should be selected at equal intervals within the useful speed range. After that, specific consumption at each operating condition must be specified within the useful range of operation.

20 6 Dynamometers have been widely used for evaluating the performance of many kinds of internal combustion engines. Many different types of dynamometer systems are in use today and detailed descriptions of the various types can be found in many book. While dynamometers make measurements of engine performance at specific loads, a large number of numerical simulations have also been developed to model the engine cycle and predict engine performance. An important advantage of these codes is that they allow the researcher to investigate the effects of specific aspects of the operating physics like friction, heat transfer and the chemistry involved in the combustion process. 2.4 THE IMPORTANCE OF ENGINE PERFORMANCE TESTING The two stroke engine was developed only in two opposite fields, namely, large marine engines which use a separate scavenging pump, and small engines for various applications such as power tool. In the former case, high efficiency is desired; in the letter case, lightness, simplicity, and high power output are sought (M. Nuti, 1998). The two stroke cycle engine was invented by Sir Dugald Clerk in England at the end of the 19 th century. The form of the engine is using crankcase compression for the introduction process, including the control of the timing and area of the exhaust, transfer and intake ports by piston (G. P. Blair, 1996).

21 7 Fig 2.2: Titan Test Stand Today the most common power source is the well-known two-stroke engine. This type of engine has been the natural choice due to low cost and high power density. The two-stroke engine, as we know it today is not able to comply with future emission demands due to its massive hydrocarbon pollutant. However, in the future engine manufactures must come up with new cost-efficient engine technologies that still deliver the same or improved performance for customer satisfaction (M. Bergman, 2003). Power and torque measurements obtained at different loading conditions show the same general trends for most conventional scale engines. As figure 1 show, both parameters increase with increasing engine speed and reach a flat peak before decreasing at higher speeds. Engine torque is usually found to peak first followed by a peak in the engine power. Transmission systems in automobiles and other applications are designed to allow the engine to operate in the relatively narrow regimes where it yields maximum power, torque and efficiency.

22 8 Fig 2.3: Typical shape of power, torque characteristics of a conventional size 2/4 - stroke engine Waltermann and Neuendorf from University Paderborn, Germany, have been developed a test bed for the design and the optimization of a series hybrid drive train (P Waltermann and N Neuendorf, 2006). For test bed control a powerful real-time environment is applied that comprises component control and the simulation of different component models as well as the operating strategy and the emergency system. All important components of a series hybrid drive are mounted. The individual components (combustion engine, generator, battery and traction drives) were controlled with the different modules. 2.5 DEVELOPMENT OF ENGINE PERFORMANCE TESTING There are so many research developments on two stroke engine. One of them has been conducted by Merrit and Bennett. The research describes a new stratified charge burn combustion management system based on the invention of a new gas dynamic segregation system (D Merritt and M C Bennett, 2006). The principles leading to high thermal efficiency are explored in relation to their adoption in the new system. Some test results taken on two different Merritt Engine prototypes are shown.

23 9 Thermal efficiency values obtained compare very favorably with the latest published result for advanced automobile. There are shown at this current stage of development and it is reasonable to expect further improvements. Improvements should follow the availability of a suitable fuel injection system, improved combustion chamber design, further reduction of combustion chamber heat losses and of course turbo charging in suitable applications. Another research has been developed by Gordon. 100 cc of two stroke diesel engine was used to investigate the drawbacks of the injection system. The ultimate performance was limited by a mechanical fuel injection system (RL Gordon, 2005). The weakness could be consisted by used a high pressure pump, and electromagnetically actuated, balanced valve and a miniature fuel injector, as the result successfully demonstrated to offer full flexibility in injection timing and fuel delivery. A weight saving of up to 25% was also shown, proving the viability of the new, miniature fuel injection system concept. A new piston-crank system incorporating a multiple-link mechanism to obtain the optimum compression ratio (VCR) mechanism can be installed without increasing the engine size or weight substantially by selecting a suitable type of link mechanism and optimizing the detailed specifications (Ryosuke, Shunichi and Takanobu, 2006). The effect of these characteristics on fuel economy and maximum power under part load operation was maximum power under part load operation was made clear in terms of combustion stability, time loss, cooling loss and friction. Research towards improving the performance of internal combustion engines is important because they are ubiquitous. From Michael Anthony Prados, he concluded that it is possible to replace crankshaft from linear motion into rotary motion, to generate electric power (Michael, 2004). The advantage of this technology is easier to define a motion of piston. He used four stroke engines to gain his results because consist of a single unopposed cylinder, which mean this engine has small scale. However, this engine

24 10 cannot produce too much power but this is good because from experiment conduct, it will be a platform to improve linear engine for power generation. Vong Chi-man and Wong Pak-Kin had design and model of modern automotive petrol engine performance. They used Support Vector Machines to utilize the results. With an emerging technique, Support Vector Machines (SVM), the approximate performance model of a petrol vehicle engine can be determined by training the sample engine performance data acquired from the dynamometer (Vong and Wong, 2004). They found that current practice of engine tune-up relies on the experience of the automotive engineer, and tune-up is usually done by trial-and-error method and then the vehicle engine is run on the dynamometer to show the actual engine performance. The authors found that the number of dynamometer tests for an engine tune-up can therefore be reduced because the estimated engine performance model can replace the dynamometer tests to a certain extent. 2.6 DYNAMOMETER Dynamometer is a device to measure force, torque, or power. For example, the power produced by an engine, motor or other rotating prime mover can be calculated by simultaneously measuring torque and rotational speed (rpm). In standard emissions testing cycles, dynamometers are used to provide simulated road loading of either the engine (using an engine dynamometer) or full powertrain (using a chassis dynamometer). In fact, beyond simple power and torque measurements, dynamometers can be used as part of a test rig for a variety of engine development activities such as the calibration of engine management controllers, detailed investigations into combustion behavior.